USB: add urb->unlinked field

This patch (as970) adds a new urb->unlinked field, which is used to
store the status of unlinked URBs since we can't use urb->status for
that purpose any more.  To help simplify the HCDs, usbcore will check
urb->unlinked before calling the completion handler; if the value is
set it will automatically override the status reported by the HCD.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
CC: Olav Kongas <ok@artecdesign.ee>
CC: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
CC: Tony Olech <tony.olech@elandigitalsystems.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index 0cb0325..f2b124c 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -1029,8 +1029,7 @@
 static void maybe_set_status (struct urb *urb, int status)
 {
 	spin_lock (&urb->lock);
-	if (urb->status == -EINPROGRESS)
-		urb->status = status;
+	urb->status = status;
 	spin_unlock (&urb->lock);
 }
 
@@ -1257,10 +1256,9 @@
 		int			type;
 
 		urb = urbp->urb;
-		if (urb->status != -EINPROGRESS) {
-			/* likely it was just unlinked */
+		if (urb->unlinked)
 			goto return_urb;
-		} else if (dum->rh_state != DUMMY_RH_RUNNING)
+		else if (dum->rh_state != DUMMY_RH_RUNNING)
 			continue;
 		type = usb_pipetype (urb->pipe);